Aeroelastic characteristics and vibration reduction method of NTBT rotor with TEF technology

A high-precision CFD/CSD (Computational Fluid Dynamics/Computational Structural Dynamics) coupling method is developed to study the aeroelastic behavior and design the vibration reduction strategy of NTBT (New Type Blade-Tip) rotor with TEF (Trailing Edge Flap) technology in forward flight. In the aspect of CSD method, the closed-form dynamical governing equation is modified using Hamilton’s principle to consider the influence of the movable TEF, in which the NTBT geometric nonlinearity is considered through coordinate transformation by virtue of finite element method. In the aspect of CFD method, a moving-embedded grid method for rotor blades is developed to account for the dynamic deflection of TEF, in which the grid deformation is achieved through algebraic transformations, and a high-precision unsteady CFD method with 5th-order TENO (Targeted Essentially Non-Oscillatory) scheme is introduced to effectively simulate the rotor flowfield. Considering the computational efficiency, the loosely-coupling strategy is introduced to build up the CFD/CSD method. The validity of the coupling method is verified by comparing the computed aerodynamic loads, frequency spectrum, and structural loads with the referential or the experimental results of the typical model rotors. Based on that, the frequency, phase, and amplitude-sweeping parametric analyses of TEF are conducted thoroughly to reveal the influence mechanisms on the aeroelastic characteristics of NTBT rotor. Furthermore, an optimal control strategy is proposed to suppress the vibration intensity of hub loads, showing that the active vibration reduction method can effectively suppress the rotor hub vibratory intensity by over 40% in typical forward flight conditions.